CTLA4 and hepatocellular carcinoma: ICIs, such as atezolizumab, nivolumab, pembrolizumab, durvalumab, ipilimumab and tremelimumab are antibodies that target regulatory immune checkpoints, including the cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) and programmed cell death protein 1 (PD-1) pathways, and have shown substantial clinical efficacy in the treatment of advanced HCC (18, 19).